In a mechanical seal which is an example of a sliding component, the performance of the mechanical seal is evaluated according to a leakage rate, a wear rate, and torque. In the related art, the sliding material properties and the sliding face roughness of the mechanical seal are optimized to improve the performance, realizing low leakage, long life, and low torque. However, due to the growing awareness of environmental problems in recent years, there is a demand for further improvement in the performance of the mechanical seal and technical development beyond the framework of the related art has been required.
Under such circumstances, the inventor of the present invention has confirmed that, for example, in a mechanical seal of a water pump which is used in the cooling of a water-cooled engine, as time passes, an additive of LLC, which is one kind of antifreeze, for example, silicate, phosphate, or the like (hereinafter referred to as “deposit generation causing substance”) is concentrated on the sliding face to generate a deposit, whereby the function of the mechanical seal may deteriorate. The generation of the deposit is considered to occur in a similar manner in a mechanical seal of equipment which handles a chemical or an oil.
In the conventionally known mechanical seals, in order to prevent the occurrence of wear and burning due to frictional heat generation on the sliding face, a groove is formed on the sliding face such that a fluid layer is formed between the sliding faces (for example, refer to Patent Documents 1, 2, and 3); however, these inventions relate to introducing a fluid to the sliding face, and in these inventions, measures have not been taken to prevent the generation of a deposit on the sliding face.